Endo-N-(9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1-methyl-1H-indazole-3-carboxamide hydrochloride, its use as an anti-emetic, particularly in the treatment of cytotoxic agent induced emesis, and methods for its synthesis are disclosed in U.S. Pat. No. 4,886,808. Endo-N-(9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1-methyl-1H-indazole-3-carboxamide hydrochloride is commercially available and is also known by the generic name granisetron hydrochloride.
An injectable dosage form of endo-N-(9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1-methyl-1-indazole-3-carboxamide hydrochloride was first commercialized as a 1 mL single use vial containing an aqueous solution comprising 1.12 mg of granisetron hydrochloride equivalent to granisetron 1 mg. The recommended dosage for granisetron hydrochloride is 10 mcg/kg infused intravenously over 5 minutes, beginning within 30 minutes before initiation of chemotherapy.
The 1 mg/mL single dose vial has proved undesirable in a number of ways. The recommended dose is 10 mcg/kg of body weight. Thus, the 1 mL vial is not optimal for patients weighing greater than 100 kg, and a portion of a second vial will have to be utilized and the remaining medication discarded. Similarly, product wastage will occur when administering to lighter patients who do not require the full 1 mL dose. Numerous advantages are realized from a suitable multidose vial of endo-N-(9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1-methyl-1H-indazole-3-carboxamide hydrochloride. The advantages of a multidose vial of endo-N-9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1-methyl-1H-indazole-3-carboxamide hydrochloride include: making weight-based dosing more efficient thereby minimizing wasted product, conserving resources, containing costs, making better use of storage space and more cost-effective to produce and transport.
U.S. Pat. No. 6,294,548 discloses a multi-dose aqueous formulation of endo-N-(9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1-methyl-1H-indazole-3-carboxamide hydrochloride and a host of possible preservatives, including meta-cresol, benzyl alcohol, methylparaben, propylparaben and a combination of methylparaben and propylparaben. According to the patent, the parabens are effective as preservatives, but unstable in autoclaving. Autoclaving is preferred by most regulatory agencies for ensuring sterility of pharmaceutical formulations.
It has now been found that certain combinations of preservatives and buffer systems yield formulations that are suitably stable during autoclaving. More particularly, it has been found that a pharmaceutical formulation comprising endo-N-(9-methyl-9-azabicyclo[3.3.1]non-3-yl)-1-methyl-1H-indazole-3-carboxamide hydrochloride, one or more preservatives selected from the group consisting of alkyl paraben and phenol, and a buffer selected from the group consisting of acetate and phosphate buffers can be autoclaved to yield a sterile multi-dose formulation.